Color composition and inkjet recording method

ABSTRACT

A coloring composition containing a dis-azo compound or poly-azo compound which contains two or more substituents having a pKa value in water of −i0 to 5 and which has an oxidation potential more positive than 0.8 V (vs SCE), and an inkjet recording ink composition containing the coloring composition and an inkjet recording method wherein an image is formed on an image-receiving material containing a support having provided thereon an ink receiving layer containing a white inorganic pigment particle, using the inkjet recording ink composition.

TECHNICAL FIELD

The present invention relates to a coloring composition such as an inkcomposition containing an azo compound having specific physicalproperties, an inkjet recording ink composition, and an inkjet recordingmethod.

BACKGROUND ART

In recent years, the mainstream of image-recording materials has beenmaterials for forming color images in particular. More specifically,recording materials based on inkjet recording, recording materials basedon heat-sensitive image transfer, recording materials based onelectronic photography, silver halide photosensitive materials based ontransfer, printing inks, recording pens, and the like have been widelyutilized. Moreover, in image pickup devices such as CCD inpicture-taking instruments and in LCD and PDP as displays, color filtersare employed for recording and reproducing color images.

In these color image recording materials and color filters, coloringmatter (dyes or pigments) of three primary colors for so-called additivecolor mixing or subtractive color mixing are employed for reproducing orrecording full-color images. However, there actually exists no coloringmatter which has absorption properties capable of realizing a preferablecolor reproduction range and which is fast enough to endure various useconditions and environmental conditions, so that improvement is stronglydesired.

Because of inexpensive material costs, capability of high-speedrecording, reduced noise in recording operations, and ease in colorrecording, inkjet recording has rapidly come into wide use and is stillmaking further progress.

Inkjet recording methods include a continuous method in which liquiddroplets are jetted continuously and a on-demand method in which liquiddroplets are jetted depending on signals of image information, andejection methods thereof include a method in which liquid droplets,pressed by a piezoelectric element, are ejected, a method in whichliquid droplets are ejected by bubbles generated in the ink by heat, amethod in which ultrasonic waves are used, and a method in which liquiddroplets are suction-ejected by electrostatic force.

Moreover, as an inkjet recording ink composition, aqueous ink, oil-basedink, and solid (fusion-type) ink are used.

The properties required for the coloring matter in such an inkjetrecording ink composition are satisfactory solubility or dispersibilityin a solvent, capability of high-density recording, excellent hue,fastness to light, heat, and active gases (oxidizing gases such asNO_(x) and ozone, SO_(x), etc.) in the environment, excellent fastnessto water and chemicals, excellent fixation and little bleeding onimage-receiving materials, excellent storability as ink, freedom fromtoxicity, high purity, and availability at a low cost.

However, it is extremely difficult to obtain coloring matter that highlysatisfies these requirements. In particular, there is a strong demandfor coloring matter that has a satisfactory hue and exhibits fastness tolight, humidity, and heat, and particularly, when printing is carriedout on an image-receiving material having an ink-receiving layercontaining porous white inorganic pigment particles, it is stronglydesired that the coloring matter exhibits fastness to oxidizing gasessuch as ozone in the environment.

Heretofore, as a coupling component for azo dyes, phenol, naphthol,aniline, and the like have been widely used. As azo dyes obtainable fromthese coupling components, dyes disclosed in EP0761771, Japanese PatentNo. 2716541, and so forth are known, for example, but these dyes have aproblem of inferior lightfastness.

Moreover, any dyes known in the conventional art exhibit extremelyinsufficient fastness to oxidizing gases such as ozone.

The present inventors have investigated to develop a dye exhibitingfastness to oxidizing gases such as ozone and have conceived to use anitrogen-containing heterocyclic compound as the coupling componentdeparting from the conventional coupling components such as phenol,naphthol, and aniline. Heretofore, azo dyes using pyridine or pyrazineas the coupling component have been described, for example, in GermanPatent No. 2743097. However, the use of these dyes for inkjet recordingink was not known at that time. This is because these dyes are alloil-soluble and it is difficult to synthesize water-soluble counterpartsof these dyes. Therefore, it was impossible to synthesize water-solublecounterparts of these dyes and to employ ink containing such dyes forimage formation such as inkjet recording.

The invention aims at solving the above problem in the conventional artand achieving the following object.

Namely, it is an object of the invention to provide:

-   (1) various coloring compositions such as a printing ink composition    (e.g., inkjet recording ink) which afford colored images and colored    materials excellent in water resistance and fastness using a novel    azo compound having an excellent water resistance and a sufficient    fastness to light, heat, humidity, and active gases in the    environment as a black dye, and-   (2) an inkjet recording ink composition and an inkjet recording    method capable of forming images having an excellent water    resistance and a high fastness to light and active gases in the    environment, particularly ozone gas.

DISCLOSURE OF THE INVENTION

As a result of precise investigation for aiming at a dye having anexcellent water resistance and a high fastness to light and ozone, theinventors have found that an azo compound having a specific oxidationpotential exhibits an unexpectedly high fastness, and thereforeaccomplished the invention.

According to the invention, a coloring composition having the followingconstitution, an inkjet recording ink composition, and an inkjetrecording method are provided, and thereby the above object of theinvention is achieved.

(1) A coloring composition comprising a dis-azo compound or poly-azocompound which contains two or more substituents having a pKa value inwater of −10 to 5 and which has an oxidation potential more positivethan 0.8 V (vs SCE).

(2) The coloring composition described in the above (1), wherein thedis-azo compound or poly-azo compound is an azo compound represented bythe following general formula (I):A-N═N—B—N═N—C  (I)wherein A, B, and C each independently represents an aromatic groupwhich may be substituted or a heterocyclic group which may besubstituted, A and C are monovalent groups and B is a divalent group.

(3) The coloring composition described in the above (1), wherein thedis-azo compound or poly-azo compound is an azo compound represented bythe following general formula (II):A-N═N—B—N═N-Het  (II)wherein A and B are the same as A and B in the general formula (I)respectively, and Het represents an aromatic heterocyclic group.

(4) The coloring composition described in the above (3), wherein atleast one of A and B in the general formula (II) is an aromaticheterocyclic group.

(5) The coloring composition described in the above (3), wherein Het inthe general formula (II) is an aromatic nitrogen-containing six-memberedheterocyclic group.

(6) The coloring composition described in the above (3), wherein thedis-azo compound or poly-azo compound is an azo compound represented bythe following general formula (III):

wherein A and B are the same as A and B in the general formula (II)respectively, B₁ and B₂ represent ═CR₁— and —CR₂═ respectively, oreither one represents a nitrogen atom and the other represents ═CR₁— or—CR₂═; G, R₁ and R₂ each independently represents a hydrogen atom, ahalogen atom, an aliphatic group, an aromatic group, a heterocyclicgroup, a cyano group, a carboxyl group, a carbamoyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclicoxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group, anaryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxygroup, a carbamoyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group (including an anilino group anda heterocyclic amino group), an acylamino group, a ureido group, asulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkyl- or arylsulfonylamino group, aheterocyclic sulfonylamino group, a nitro group, an alkyl- or arylthiogroup, a heterocyclic thio group, an alkyl- or arylsulfonyl group, aheterocyclic sulfonyl group, an alkyl- or arylsulfinyl group, aheterocyclic sulfinyl group, a sulfamoyl group, or a sulfo group, andeach of these groups may further be substituted; R₅ and R₆ eachindependently represents a hydrogen atom, an aliphatic group, anaromatic group, a heterocyclic group, an acyl group, an alkoxycarbonylgroup, an aryloxycarbonyl group, a carbamoyl group, an alkyl- orarylsulfonyl group, or a sulfamoyl group, and each of these groups mayfurther be substituted, provided that R₅ and R₆ are not hydrogen atomsat the same time; and R₁ and R₅ or R₅ and R₆ may be combined to form afive-membered or six-membered ring.

(7) The coloring composition described in the above (6), wherein thedis-azo compound or poly-azo compound is an azo compound represented bythe following general formula (IV):

wherein A, B₁, B₂, G, R₅ and R₆ are the same as A, B₁, B₂, G, R₅ and R₆in the general formula (III) respectively, and R₇ and R₈ are the same asR₁ in the general formula (III).

(8) An inkjet recording ink composition, which comprises the coloringcomposition described in any one of the above (1) to (7).

(9) An inkjet recording method, wherein an image is formed on animage-receiving material comprising a support having provided thereon anink receiving layer containing a white inorganic pigment particle, usingthe inkjet recording ink composition described in the above (8).

(10) A method for improving ozone gas-fastness of an image formed on animage-receiving material comprising a support having provided thereon anink receiving layer containing a white inorganic pigment particle usingan inkjet recording ink composition, wherein the inkjet recording inkcomposition is the inkjet recording ink composition described in theabove (8).

BEST MODE FOR CARRYING OUT THE INVENTION

The following will explain the present invention in detail.

The requirements for the azo compound to be contained in the coloringcomposition of the invention are to have an oxidation potential morepositive than 0.8 V (vs SCE) and to contain two or more substituentshaving a pKa value in water of −10 to 5.

A more positive oxidation potential is more preferred, and the oxidationpotential is preferably more positive than 1.0 V (vs SCE), morepreferably more positive than 1.1 V, and further preferably morepositive than 1.2 V (vs SCE).

The above requirements of the invention are based on the findings, whichare shown by the inventors in their study on ozone gas-fastness ofcolored images, that there is a correlation between the oxidationpotential of a compound for use in the colored images and ozonegas-fastness and the use of a compound having an oxidation potentialvalue more positive than 0.8 V against saturated calomel electrode (SCE)improves ozone gas-fastness and that an unexpectedly high ozonegas-fastness is observed when the azo compound is an azo compoundcontaining two or more substituents whose pKa value in water is from −10to 5.

The reason for the improvement of ozone gas-fastness of colored imagesis as follows. It is considered that a colored compound is decomposedthrough oxidation owing to the relationship between HOMO (highestoccupied molecular orbital) and LUMO (lowest unoccupied molecularorbital) of the compound and ozone gas, i.e., by the reaction betweenHOMO of the azo compound and LUMO of ozone gas, and thereby density ofthe colored images is lowered. For this reason, it is presumed that theuse of an azo compound having a specific oxidation potential results indecreased HOMO of the compound to lower its reactivity with ozone gas,and hence ozone gas-fastness thereof is enhanced.

In this regard, the value of the oxidation potential stands for easinessof the movement of an electron from a sample to an electrode. Thus, itmeans that the larger the value (the more positive the oxidationpotential), the more difficult the movement of the electron from thesample to the electrode is, in other words, the more difficult theoxidization is. With regard to the relationship with the structure of acompound, the oxidation potential becomes more positive when anelectron-withdrawing group is introduced and the oxidation potentialbecomes more negative when an electron-donating group is introduced.

The value of the oxidation potential will be precisely described belowbut the value means electric potential at which an electron of acompound is taken out at an anode in voltammetry of the compound, and isconsidered to coincide approximately with the energy level of HOMO inthe ground state of the compound.

Measurement of the oxidation potential will be specifically explained.The oxidation potential is determined by dissolving a test sample in aconcentration of 1×10⁻⁴ to 1×10⁻⁶ mol·dm⁻³ in a solvent such asdimethylformamide or acetonitrile containing a supporting electrolytesuch as sodium perchlorate or tetrapropylammonium perchlorate andmeasuring a value against SCE (saturated calomel electrode) using cyclicvoltammetry or direct current polarography.

Moreover, the supporting electrolyte and solvent to be used may besuitably selected depending on the oxidation potential and solubility ofthe test sample. Usable supporting electrolytes and solvents aredescribed in, for example, Delahay, New Instrumental Methods inElectrochemistry, (1954) by Interscience Publishers; A. J. Bard, et al.,Electrochemical Methods, (1980), by John Wiley & Sons; and AkiraFujishima, et al., Denkikagaku Sokuteiho (Electrochemical MeasurementMethods), pp. 101-118, (1984), by Gihodo Shuppan.

The value of the oxidation potential may deviate by about several tensmillivolts by influences such as a liquid potential and a liquidresistance of the sample solution, but it is possible to guarantee thereproducibility of the potential by calibration with a standard sample(e.g., hydroquinone).

As the oxidation potential in the invention, a value obtained bydissolving a compound in a concentration of 1×10⁻³ mol·dm⁻³ in a mixedsolution of water/N,N-dimethylformamide=2/98 containing 0.1 mol·dm⁻³ oftetrapropylammonium perchlorate as a supporting electrolyte andmeasuring a potential by direct current polarography using SCE(saturated calomel electrode) as a reference electrode, a graphiteelectrode as a working electrode and a platinum electrode as a counterelectrode is adopted.

Moreover, the methods for making the oxidation potential positive in theinvention include a method of selecting a compound whose structureitself has a positive potential, a method of introducing anelectron-withdrawing group at any position, i.e., a method ofintroducing a substituent having a large value of the Hammett'ssubstituent constant, σp value as a measure of the electron-withdrawinggroup or electron-donating group, and the like. The method of selectinga dye structure originally having a positive oxidation potential ispreferable not only in view of ozone gas-fastness but also in view ofmolecular design since an electron-withdrawing group orelectron-donating group can be arbitrarily introduced in order tocontrol other fastness, hue, and physical properties.

Furthermore, in the method of introducing an electron-withdrawing groupat any position of the structure of a compound to make the oxidationpotential more positive for the purpose of lowering reactivity withozone as an electrophile, the oxidation potential can be made morepositive by introducing a substituent having a large σp value when theHammett's substituent constant, up value as a measure of theelectron-withdrawing group or electron-donating group is adopted.

The Hammett's substituent constant, σp value will be described. TheHammett's rule is an empirical rule advocated by L. P. Hammett in 1953in order to quantitatively discuss the influence of substituents on thereaction or equilibrium of benzene derivatives, and propriety of thisrule is now widely recognized. The substituent constant required for theHammett's rule includes a σp value and a cm value. These values can befound in many general books. For example, the details are given in J. A.Dean ed., Lange's Handbook of Chemistry, 12th Ed. (1979), byMcGraw-Hill; and a special issue of Kagaku no Ryoiki (Regions ofChemistry), No. 122, pp. 96-103 (1979), by Nankodo. Needless to say,while in the invention, each substituent will be limited or described interms of the Hammett's substituent constant σp value, this does not meanthat the invention is limited only to substituents having known valuesthat can be found from the foregoing general books, but the inventionalso includes substituents, values of which are unknown but will fallwithin the intended scope when measured according to the Hammett's rule.Furthermore, though compounds that are not a benzene derivative areincluded within the scope of the general formulae (I) and (II) of theinvention, the σp values are used as a measure to exhibit the electroniceffect of the substituent irrespective of the substitution position. Inthe invention, the σp value is used in such meanings.

In addition, as mentioned above, the requirement for the azo compound tobe contained in the coloring composition of the invention is to containtwo or more substituents having a pKa value in water of −10 to 5. ThepKa value is preferably from −9 to 5, and more preferably from −8 to 5.

The substituent having a pKa value in water of −10 to 5 is a substituentwhich represents a moiety of the proton-dissociating group of a compoundwhose pKa value in water is from −10 to 5.

The pKa value is a value represented in accordance with the definitiondescribed in Yasuhiko Sawaki, Kiso Kagaku kosu (Basic Chemistry Course)Butsuri Yuki Kagaku (Physical Organic Chemistry), pp. 47-60 (1999), byMaruzen. The pKa values of various compounds are given in Table 8.1 ofM. B. Smith and J. March, March's Advanced Organic Chemistry, 5thedition, p. 329 (2001), by John Wiley & Sons, and literatures citedtherein. From the values, the pKa value of a substituent may be deduced.The pKa value of compounds not described therein can be determined fromthe definition of pKa value in accordance with the measuring methoddescribed in the Chemical Society of Japan ed., Jikken Kagaku Koza(Lecture on Experimental Chemistry) 1, 4th edition, Kihon Sosa (BasicOperations) I, p. 115 (1990), by Maruzen. The pKa value of a weak acidcan be also determined as a relative value in accordance with the methoddescribed in Yasuhiko Sawaki, Kiso Kagaku kosu (Basic Chemistry Course)Butsuri Yuki Kagaku (Physical Organic Chemistry), p. 50 (1999), byMaruzen. Alternatively, since the pKa value varies depending onenvironmental conditions such as solvent, the value can be alsodetermined in accordance with the method described in the ChemicalSociety of Japan ed., Jikken Kagaku Koza (Lecture on ExperimentalChemistry) 9, 4th edition, Denki/Jiki (Electricity/Magnetism), p. 286(1991), by Maruzen.

However, since the pKa value of a certain substituent in a compound isgreatly influenced by the structure of the compound, the actual value issometimes different from the value estimated from the other compound.Though it is possible to measure actually the pKa value of thedissociating group in the compound in accordance with the aforementionedmethods, it is not easy to understand the value systematically owing toidentification of the resulting values and possible influence of themeasurement on the moiety other than the dissociating group.

Therefore, in the invention, the pKa value of a certain substituent isnot represented by a measured value in the compound but is representedby a general pKa value of the corresponding functional group.

In this case, it is preferable to carry out estimation by using a valuecapable of minimizing influence of substituent effect and steric effect,i.e., the pKa value of the dissociating group on a compound having astructure wherein the structure near to the dissociating group issimilar. For example, the pKa value of the carboxyl group bonded to abenzene ring present in a certain compound A can be expressed by the pKavalue (4.2) of benzoic acid or the pKa value of a benzoic acidderivative wherein substituent(s) and position of substitution aresimilar to those of the benzene ring in the compound A.

In the invention, the pKa value used for defining the range of physicalproperties of a compound is a pKa value in water.

Specific examples of the substituent having a pKa value in water of −10to 5 include a sulfo group, a carboxyl group, a thiocarboxyl group, asulfino group, a phosphono group, a dihydroxyphosphino group, and thelike. Preferred are a sulfo group and a carboxyl group.

Incidentally, in the invention, the dissociating group is expressed inan undissociated form or a form where a counter ion is present, but anactual compound may be present in a dissociated form or in anundissociated form or in a mixed state thereof in any ratio. Actually,the existing state varies depending on the environment in which thecompound is present.

In the invention, the number of the substituents having a pKa value inwater of −10 to 5 is two or more, but is preferably three or more, andmore preferably four or more.

The substituent having a pKa value in water of −10 to 5 may be presentat any position in the compound and the substituting positions of theindividual substituents can be independently chosen.

However, based on the description of the factors of directness towardcellulose fibers in Kazuo Kondo ed., Senshoku (dyeing), 3rd edition,(1987), by Tokyo Denki University Publishing, the substituents may bedesirably present not in adjacent positions but at appropriate intervalsin the case that they are water-soluble groups.

The substituents whose pKa value in water is from −10 to 5 and which arepresent in an amount of two or more in the compound are preferablypresent at least one per each of the two or more rings, and morepreferably two or more per each ring. For example, in the case of thecompound represented by the general formula (I) which is a preferableazo compound in the invention as described in detail below, preferred isthe case that there exist two rings on which at least one suchsubstituent is present, and more preferred is the case that there existtwo rings on which two or more such substituents are present.

The reason why colored images obtained by using a coloring compositionof the invention containing a specific azo compound are excellent inozone gas resistance is considered to be that, in addition to the abovepresumption, the presence of appropriate number of suitable dissociatinggroups at appropriate positions in the molecule improves directness ofthe azo compound and thereby the azo compound in the ink can be fixed ata desirable position in the image-receiving material and is stronglymordanted in an image-receiving material or an image-receiving layer.This is consistent with the results of water resistance test in Exampleswhich will be detailed below.

Namely, if the azo compound is strongly mordanted in an image-receivingmaterial or an image-receiving layer and hence colored images having asatisfactory water resistance is provided, the strength of dyeing can beestimated by a water resistance test. As a matter of fact, in Examplesof the invention which will be detailed below, those having asatisfactory ozone gas resistance also have satisfactory waterresistance, so that it is realized that mordanting is relevant to ozonegas resistance.

Each group of A, B, and C in the general formula (I) represents anaromatic group such as an aryl group or a heterocyclic group, but C ispreferably an aromatic heterocyclic group (Het). At lest one of A and Bis also preferably an aromatic heterocyclic group, and in particular, atleast B is preferably an aromatic heterocyclic group. The aboveheterocyclic group is a five-membered to seven-membered ring andpreferably contains N, S, and/or O as heteroatom(s). A fused one is alsoincluded.

In the general formulae (I) and (II), in the case that B is aheterocyclic group, preferable heterocylces include a thiophene ring, athiazole ring, an imidazole ring, a benzothiazole ring, a thienothiazolering, and the like. Of these, preferred are a thiophene ring, a thiazolering, an imidazole ring, a benzothiazole ring, and a thienothiazole ringrepresented by the following general formulae (a) to (e). In thisregard, most preferably, B is a heterocyclic group derived fromthiophene ring represented by the general formula (a).

In the above general formulae (a) to (e), R₁₀ to R₁₈ representsubstituents having the same meanings as R₁ in the general formula(III).

B may further have substituent(s) and examples of the substituentsinclude a halogen atom, an alkyl group (including a cycloalkyl group anda bicycloalkyl group), an alkenyl group (including a cycloalkenyl groupand a bicycloalkenyl group), an alkynyl group, an aryl group, aheterocyclic group, a cyano group, a hydroxyl group, a nitro group, acarboxyl group, an alkoxy group, an aryloxy group, a silyloxy group, aheterocyclic oxy group, an acyloxy group, a carbamoyloxy group, analkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group(including an anilino group), an acylamino group, an aminocarbonylaminogroup, an alkoxycarbonylamino group, an aryloxycarbonylamino group, asulfamoylamino group, an alkylsulfonylamino group, an arylsulfonylaminogroup, a mercapto group, an alkylthio group, an arylthio group, aheterocyclic thio group, a sulfamoyl group, a sulfo group, analkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, anarylsulfonyl group, an acyl group, an aryloxycarbonyl group, analkoxycarbonyl group, a carbamoyl group, an arylazo group, aheterocyclic azo group, an imido group, a phosphino group, a phosphonogroup, a phosphinyl group, a phosphinyloxy group, a phosphinylaminogroup, and a silyl group.

Among the above functional group, those having a hydrogen atom may besubstituted with the above group while removing the hydrogen atom.Examples of such substituents include an alkylcarbonylaminosulfonylgroup, an arylcarbonylaminosulfonyl group, an alkylsulfonylaminocarbonylgroup, an arylsulfonylaminocarbonyl group, and the like.

A fused ring of a hydrocarbon ring or a heterocycle may be formed bycombining the substituents on these heterocycles each other, andsubstituent(s) may be present on the fused ring. In the case of anitrogen-containing heterocycle, the nitrogen atom may be converted intoquaternary one. Moreover, with regard to the heterocycle capable oftautomerization, even when only one tautomer is described, the compoundalso includes the other tautomer(s).

Moreover, Het represents an aromatic heterocyclic group, preferably anaromatic nitrogen-containing heterocyclic group, especially afive-membered or six-membered aromatic nitrogen-containing heterocyclicgroup, and more preferably an aromatic nitrogen-containing heterocyclicgroup represented by the general formula (V).

In the general formula (V), B₁ and B₂ each represents ═CR₁— or —CR₂═, oreither one represents a nitrogen atom and the other represents ═CR₁— or—CR₂═. More preferably, each represents ═CR₁— or —CR₂═.

R₅ and R₆ each independently represents a hydrogen atom, an aliphaticgroup, an aromatic group, a heterocyclic group, an acyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkyl- or arylsulfonyl group, or a sulfamoyl group, and each of thesegroups may further be substituted. Preferable substituents representedby R₅ and R₆ include a hydrogen atom, an aliphatic group, an aromaticgroup, a heterocyclic group, an acyl group, and an alkyl- orarylsulfonyl group. More preferred are a hydrogen atom, an aromaticgroup, a heterocyclic group, an acyl group, and an alkyl- orarylsulfonyl group. Most preferred are a hydrogen atom, an aryl group,and a heterocyclic group. Each of these groups may further besubstituted. However, R₅ and R₆ are not hydrogen atoms at the same time.

G, R₁ and R₂ each independently represents a hydrogen atom, a halogenatom, an aliphatic group, an aromatic group, a heterocyclic group, acyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonylgroup, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, anacyl group, a hydroxyl group, an alkoxy group, an aryloxy group, aheterocyclic oxy group, a silyloxy group, an acyloxy group, acarbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxygroup, an amino group (including an anilino group and a heterocyclicamino group), an acylamino group, a ureido group, a sulfamoylaminogroup, an alkoxycarbonylamino group, an aryloxycarbonylamino group, analkyl- or arylsulfonylamino group, a heterocyclic sulfonylamino group, anitro group, an alkyl- or arylthio group, a heterocyclic thio group, analkyl- or arylsulfonyl group, a heterocyclic sulfonyl group, an alkyl-or arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group,or a sulfo group, and each of these groups may further be substituted.

The substituent represented by G is preferably a hydrogen atom, ahalogen atom, an aliphatic group, an aromatic group, a hydroxyl group,an alkoxy group, an aryloxy group, an acyloxy group, a heterocyclic oxygroup, an amino group (including an anilino group and a heterocyclicamino group), an acylamino group, a ureido group, a sulfamoylaminogroup, an alkoxycarbonylamino group, an aryloxycarbonylamino group, analkyl- or arylthio group, or a heterocyclic thio group; more preferablya hydrogen atom, a halogen atom, an alkyl group, a hydroxyl group, analkoxy group, an aryloxy group, an acyloxy group, an amino group(including an anilino group and a heterocyclic amino group), or anacylamino group, and most preferably a hydrogen atom, an anilino group,or an acylamino group. Each of these groups may further be substituted.

Preferred examples of the substituent represented by R₁ and R₂ include ahydrogen atom, an alkyl group, a halogen atom, an alkoxycarbonyl group,a carboxyl group, a carbamoyl group, a hydroxyl group, an alkoxy groupand cyano group. Each of these groups may further be substituted.

R₁ and R₅ or R₅ and R₆ may be combined to form a five-membered orsix-membered ring.

As the substituent with which each of the substituents represented by A,R₁, R₂, R₅, R₆, and G is substituted, the substituents as enumeratedabove for G, R₁, and R₂ can be enumerated. Moreover, it is preferable tohave further an ionic hydrophilic group as a substituent at any positionon A, R₁, R₂, R₅, R₆, and G.

The ionic hydrophilic group as a substituent includes a sulfo group, acarboxyl group, a phosphono group, and a quaternary ammonium group, andthe like. The ionic hydrophilic group is preferably a carboxyl group, aphosphono group, or a sulfo group, and particularly preferably acarboxyl group or a sulfo group. The carboxyl group, phosphono group,and sulfo group may be in the form of a salt, and examples of a counterion forming the salt include an ammonium ion, an alkali metal ion (e.g.,a lithium ion, a sodium ion, a potassium ion) and an organic cation(e.g., a tetramethylammonium ion, a tetramethylguanidinium ion, atetramethylphosphonium ion).

In the case that a substituent having a pKa value of −10 to 5 is presenton Het, the position is preferably any of R₄ to R₉, and more preferablyany of R₆ to R₉, and particularly preferably, one substituent is presentas R₆ or R₇ and the other one as R₈ or R₉.

The substituent having a pKa value of −10 to 5 may be bonded to A or Bin the general formula (I) directly or through any divalent connectinggroup. As the divalent connecting group, there may be enumerated aconnecting group which is expressed by the structure obtainable byfurther removing a hydrogen atom or a substituent from theabovementioned substituent (a monovalent substituent) that B may have.Examples thereof include an alkylene group (e.g., methylene, ethylene,propylene, butylene, or pentylene), an arylene group (e.g., phenylene,naphthylene, or 2,4,6-trimethylphenylene), an alkenylene group (e.g.,ethenylene or propenylene), an alkynylene group (e.g., ethynylene orpropynylene), an amido group, an ester group, a sulfonamido group, asulfonate ester group, a ureido group, a sulfonyl group, sulfinyl group,a thioether group, an ether group, a carbonyl group, —N(Rq)- (Rqrepresents a hydrogen atom, a substituted or unsubstituted alkyl group,or a substituted or unsubstituted aryl group), a heterocyclic divalentgroup (e.g., benzothiazol-2,6-diyl group,6-chloro-1,3,5-triazin-2,4-diyl group, pyrimidin-2,4-diyl group, orquinoxalin-2,3-diyl group), or a divalent connecting group constitutedby combining two or more of them. Moreover, the divalent connectinggroup may have any substituent.

The azo group in the azo compound to be contained in the coloringcomposition of the present invention may be present in an azo form(—N═N—) and a hydrazo form (—NH—N═) depending on the structure of thecompound, but all the compounds are expressed as the azo form in theinvention.

In addition, the azo compound may be present as various tautomersdepending on the environment where the compound is present. In theinvention, the compound is expressed as only one tautomer but may bepresent as the other tautomers and these tautomers are also included inthe invention.

In the invention, a particularly preferred structure is represented bythe following general formula (VI).

In the general formula (VI), Z₁ represents an electron-withdrawing grouphaving a Hammett's substituent constant, up value of 0.20 or more. Z₁represents preferably an electron-withdrawing group having a σp value of0.30 or more, more preferably an electron-withdrawing group having a upvalue of 0.45 or more, and particularly preferably anelectron-withdrawing group having a up value of 0.60 or more, but thevalue is desirably 1.0 or less. As preferred specific examples of thesubstituent, electron-withdrawing substituents as described later areenumerated. Especially, an acyl group having 2 to 20 carbon atoms, analkyloxycarbonyl group having 2 to 20 carbon atoms, a nitro group, acyano group, an alkylsulfonyl group having 1 to 20 carbon atoms, anarylsulfonyl group having 6 to 20 carbon atoms, a carbamoyl group having1 to 20 carbon atoms, and a halogenated alkyl group having 1 to 20carbon atoms are preferred. Of these, a cyano group, an alkylsulfonylgroup having 1 to 20 carbon atoms, an arylsulfonyl group having 6 to 20carbon atoms are particularly preferred, and a cyano group is mostpreferred.

R₃ and R₄ in the general formula (VI) are the same as R₁ in the generalformula (III). Each of the groups explained in the general formula (VI)may further have a substituent. In the case that each of these groupsfurther has a substituent, the substituent includes the substituentsexplained in the general formula (I), the groups exemplified as R₁, andthe ionic hydrophilic groups.

Examples of the electron-withdrawing group having a Hammett'ssubstituent constant, up value of 0.60 or more, which is represented byZ₁, include a cyano group, a nitro group, an alkylsulfonyl group (e.g.,a methanesulfonyl group), and an arylsulfonyl group (e.g., abenzenesulfonyl group).

Examples of the electron-withdrawing group having a Hammett'ssubstituent constant, up value of 0.45 or more include, in addition tothe above substituents, an acyl group (e.g., an acetyl group), analkoxycarbonyl group (e.g., a dodecyloxycarbonyl group), anaryloxycarbonyl group (e.g., a m-chlorophenoxycarbonyl group), analkylsulfinyl group (e.g., an n-propylsulfinyl group), an arylsulfinylgroup (e.g., a phenylsulfinyl group), a sulfamoyl group (e.g., anN-ethylsulfamoyl group or an N,N-dimethylsulfamoyl group), and ahalogenated alkyl group (e.g., a trifluoromethyl group).

Examples of the electron-withdrawing group having a Hammett'ssubstituent constant, σp value of 0.30 or more include, in addition tothe above substituents, an acyloxy group (e.g., an acetoxy group), acarbamoyl group (e.g., an N-ethylcarbamoyl group and anN,N-dibutylcarbamoyl group), a halogenated alkoxy group (e.g., atrifluoromethyloxy group), a halogenated aryloxy group (e.g., apentafluorophenyloxy group), a sulfonyloxy group (e.g., amethylsulfonyloxy group), a halogenated alkylthio group (e.g., adifluoromethylthio group), an aryl group substituted with two or moreelectron-withdrawing groups having a σp value of 0.15 or more (e.g., a2,4-dinitrophenyl group or a pentachlorophenyl group), and aheterocyclic group (e.g., a 2-benzoxazolyl group, a 2-benzothiazolylgroup, or a 1-phenyl-2-benzimidazolyl group).

Specific examples of the electron-withdrawing group having a up value of0.20 or more include a halogen atom in addition to the abovesubstituents.

Specific examples of the azo compound contained in the coloringcomposition of the invention will be given below in the form of freeacid, but it should not be construed that the azo compound to be used inthe invention is limited thereto. Moreover, the carboxyl group,phosphono group, and sulfo group may be in the form of salt, andexamples of a counter ion forming the salt include an ammonium ion, analkali metal ion (e.g., a lithium ion, a sodium ion, a potassium ion)and an organic cation (e.g., a tetramethylammonium ion, atetramethylguanidinium ion, a tetramethylphosphonium ion).

All of the following exemplified compounds have an oxidation potentialmore positive than 0.8 V (vs SCE).

TABLE 1

A B C (a-1)

(a-2)

(a-3)

(a-4)

(a-5)

(a-6)

(b-1)

(b-2)

(b-3)

(b-4)

(b-5)

(b-6)

(c-1)

(c-2)

(c-3)

(c-4)

(c-5)

(c-6)

(c-7)

(d-1)

(d-2)

(d-3)

(d-4)

(d-5)

(d-6)

(e-1)

(e-2)

(e-3)

(e-4)

(e-5)

(e-6)

(e-7)

(f-1)

(f-2)

(f-3)

(f-4)

(f-5)

(f-6)

(f-7)

(g-1)

(g-2)

(g-3)

(g-4)

(g-5)

(g-6)

(h-1)

(h-2)

(h-3)

(h-4)

(h-5)

(h-6)

(i-1)

(i-2)

(i-3)

(i-4)

(i-5)

(i-6)

(i-7)

(j-1)

(j-2)

(j-3)

(j-4)

(j-5)

(j-6)

(j-7)

(k-1)

(k-2)

(k-3)

(k-4)

(k-5)

(k-6)

(k-7)

(l-1)

(l-2)

(l-3)

(l-4)

(l-5)

(l-6)

(l-7)

(m-1)

(m-2)

(m-3)

(m-4)

(m-5)

(m-6)

(m-7)

(n-1)

(n-2)

(n-3)

(n-4)

(n-5)

(n-6)

(n-7)

(o-1)

(o-2)

(o-3)

(o-4)

(o-5)

(o-6)

(o-7)

(p-1)

(p-2)

(p-3)

(p-4)

(p-5)

(p-6)

(p-7)

(q-1)

(q-2)

(q-3)

(q-4)

(q-5)

(q-6)

(q-7)

(r-1)

(r-2)

(r-3)

(r-4)

(r-5)

(r-6)

(r-7)

(s-1)

(s-2)

(s-3)

(s-4)

(s-5)

(s-6)

(s-7)

(t-1)

(t-2)

(t-3)

(t-4)

(t-5)

(t-6)

(t-7)

(u-1)

(u-2)

(u-3)

(u-4)

(u-5)

(u-6)

(u-7)

(v-1)

(v-2)

(v-3)

(v-4)

(v-5)

(v-6)

(v-7)

The dye represented by the above general formula (I) can be synthesizedby a coupling reaction of a diazo component with a coupler. Thefollowing show Synthetic Examples of the dyes represented by the generalformula (I). M/S was measured by LC/MS, ESI, Nega direct introduction.Eluting liquids for use in the measurement were Liquid A: water (0.1%triethylamine, acetic acid) and Liquid B: acetonitrile (0.1%triethylamine, acetic acid), and the measurement was carried out in aLiquid B concentration of 90%.

SYNTHETIC EXAMPLE OF DYE a-1

Into 15 ml of acetic acid and 15 ml of 85% phosphoric acid was dispersed1.5 g of a diazo component A-1, and while the liquid temperature wasmaintained at −2 to 0° C., 2.2 g of 40% nitrosylsulfuric acid was addedthereto. The resulting liquid was added under stirring to a solution of3.3 g of a coupler component B-1 dissolved in 25 ml of water, followedby 1 hour of reaction at 0 to 5° C. To the reaction liquid was added 5.0g of lithium chloride, and the precipitated crystals were filtered andwashed. The thus obtained wet cake was added to 100 ml of water, the pHof the resulting solution was adjusted to 7 to 8 with 0.1 N aqueouslithium chloride solution, and then 300 ml of isopropyl alcohol wasadded thereto. The precipitated crystals were filtered and washed. Thisoperation was performed again to obtain 2.3 g of an objective product(lithium salt of a-1) (M/S: (M−H)⁻=698, (M−2H)²⁻=348.5; λ_(max)(water)=580 nm).

The synthetic route was shown below. In the following synthetic routes,the products are shown not as lithium salts but as free acids).

SYNTHETIC EXAMPLE OF DYE c-7

Into 15 ml of acetic acid and 15 ml of 85% phosphoric acid was dispersed2.0 g of a diazo component A-2, and while the liquid temperature wasmaintained at −2 to 0° C., 2.2 g of 40% nitrosylsulfuric acid was addedthereto. The resulting liquid was added under stirring to a solution of3.0 g of a coupler component B-1 dissolved in 30 ml of water, followedby 1 hour of reaction at 0 to 5° C. To the reaction liquid was added 5.0g of lithium chloride, and the precipitated crystals were filtered andwashed. The thus obtained wet cake was added to 100 ml of water, the pHof the resulting solution was adjusted to 7 to 8 with 0.1 N aqueouslithium chloride solution, and then 300 ml of isopropyl alcohol wasadded thereto. The precipitated crystals were filtered and washed. Thisoperation was performed again to obtain 2.9 g of an objective product(lithium salt of c-7) (M/S: (M−H)⁻=778, (M−2H)²⁻=388.5; λ_(max)(water)=580 nm).

The synthetic route was shown below.

SYNTHETIC EXAMPLE OF DYE e-2

Into 7.5 ml of acetic acid and 7.5 ml of 85% phosphoric acid wasdispersed 0.75 g of a diazo component A-3, and while the liquidtemperature was maintained at −2 to 0° C., 0.77 g of 40%nitrosylsulfuric acid was added thereto. The resulting liquid was addedunder stirring to a solution of 1.20 g of a coupler component B-1dissolved in 15 ml of water, followed by 1 hour of reaction at 0 to 5°C. To the reaction liquid were added 5.0 g of lithium chloride and 30 mlof isopropyl alcohol, successively, and the precipitated crystals werefiltered and washed. The thus obtained wet cake was added to 100 ml ofwater, the pH of the resulting solution was adjusted to 7 to 8 with 0.1N aqueous lithium chloride solution, and then 300 ml of isopropylalcohol was added thereto. The precipitated crystals were filtered andwashed. This operation was performed again to obtain 1.0 g of anobjective product (lithium salt of e-2) (M/S: (M−H)⁻=786,(M−2H)²⁻=392.5; λ_(max) (water)=582 nm).

The synthetic route was shown below.

SYNTHETIC EXAMPLE OF DYE i-1

Into 20 ml of acetic acid and 20 ml of 85% phosphoric acid was dispersed1.0 g of a diazo component A-4, and while the liquid temperature wasmaintained at −2 to 0° C., 0.7 g of 40% nitrosylsulfuric acid was addedthereto. The resulting liquid was added under stirring to a solution of1.1 g of a coupler component B-1 dissolved in 30 ml of water, followedby 1 hour of reaction at 0 to 5° C. To the reaction liquid were added5.0 g of lithium chloride and 30 ml of isopropyl alcohol, successively.The precipitated crystals were filtered and washed. The thus obtainedwet cake was added to 100 ml of water, the pH of the resulting solutionwas adjusted to 7 to 8 with 0.1 N aqueous lithium chloride solution, andthen 300 ml of isopropyl alcohol was added thereto. The precipitatedcrystals were filtered and washed. This operation was performed again toobtain 0.9 g of an objective product (lithium salt of i-1) (M/S:(M−H)⁻=908, (M−2H)²⁻=453.5; λ_(max) (water)=590 nm)

The synthetic route was shown below.

In addition to the above, the following compounds were synthesized in asimilar manner to the method mentioned above.

A B C λ max (water) MS(M-H)⁻ MS(M-2H)²⁻

582 nm 786 392.5

585 nm 822 410.5

605 nm 858 428.5

594 nm 858 428.5

590 nm 908 453.5

596 nm 908 453.5

598 nm 908 453.5

612 nm 988 493.5

594 nm 936 467.5

595 nm 1068  533.5

584 nm 946 472.5

579 nm 936 467.5

558 nm 698 348.5

557 nm 712 355.5

568 nm 723 361

563 nm 732 365.5

580 nm 778 388.5

574 nm 778 388.5

579 nm 778 388.5

573 nm 778 388.5

588 nm 812 405.5

595 nm 803 401

598 nm 803 401

594 nm 846 422.5

580 nm 812 405.5

The coloring composition of the invention is not particularly limited asfar as it contains the abovementioned specific azo compound. However,the composition may contain various substances depending on theapplications of the coloring composition. For example, as an inkcomposition, the compound is dissolved or dispersed into a medium (anoil-soluble or water soluble medium) and further, it is preferable toadd additives to be mentioned later for suitably satisfying desiredproperties and performance as the ink composition.

Also, those used in the color toner composition described inJP-A-7-209912, the color filter resist composition described inJP-A-6-35182, and the thermally transferring dye-providing materialdescribed in JP-A-7-137466 may be incorporated. (The term “JP-A” as usedherein means an “unexpected published Japanese patent application”.)

The specific azo compound contained in the coloring composition of theinvention is used after adjusting the properties such as solubility,dispersibility, and thermal mobility so as to be suitable for individualuses by substituents. Moreover, the specific azo compound contained inthe coloring composition of the invention may be used in a dissolvedstate or an emulsified or dispersed state, or even in a solid dispersedstate depending on the system to be used.

The applications of the coloring composition of the invention containingthe specific azo compound include various image-recording materials forthe formation of images, in particular color images, more specifically,inkjet recording materials, heat-sensitive recording materials,pressure-sensitive recording materials, electrophotographic recordingmaterials, transfer-type silver halide photosensitive materials,printing inks, recording pens, ink compositions, and the like. Preferredapplications include ink compositions and inkjet recording materials.

Moreover, the coloring composition can be also applied to solid imagepickup devices such as CCD, color filters for recording and reproducingcolor images for use in displays such as LCD and PDP, and dyeingsolutions for dyeing various fabrics.

The following will describe an ink composition as a preferablecomposition comprising the abovementioned coloring composition,particularly an inkjet recording ink composition in detail.

[Ink Composition]

An ink composition, for example an inkjet recording ink composition canbe prepared by dissolving and/or dispersing the abovementioned specificazo compound in a lipophilic medium or an aqueous medium. Preferably, anaqueous medium is used. As required, the other additives areincorporated within a range where the effects of the invention areimpaired. Examples of the other additives include known additives suchas a drying inhibitor (a wetting agent), a emulsion stabilizer, apenetration accelerator, a ultraviolet ray absorber, a fading-preventingagent, an anti-fungal agent, a pH regulator, a surface tensionregulator, an antifoaming agents, a preservative, a viscosity regulator,a dispersing agent, a dispersion stabilizer, a rust proofing agent, achelating agent, and the like. In the case of water-soluble ink, thesevarious additives are directly added to the ink liquid. In the case thatan oil-soluble dye is used in a dispersion form, the additives aregenerally added to a dye dispersion after its preparation but they maybe added to an oily phase or an aqueous phase at the preparation.

The drying inhibitor is suitably used for the purpose of preventingclogging of an ink injection port of a nozzle to be used in the inkjetrecording mode, the clogging being caused by drying of the inkjetrecording ink.

The drying inhibitor is preferably a water soluble organic solventhaving a vapor pressure lower than water. Specific examples thereofinclude polyhydric alcohols represented by ethylene glycol, propyleneglycol, diethylene glycol, polyethylene glycol, thiodiglycol,dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetyleneglycol derivatives, glycerin, trimethylol propane, and the like; loweralkyl ethers of polyhydric alcohols, such as ethylene glycol monomethyl(or monoethyl) ether, diethylene glycol monomethyl (or monoethyl) ether,triethylene glycol monoethyl (or monobutyl) ether or the like;heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone,1,3-dimethyl-2-imidazolidinone, N-ethylmorpholine and the like;sulfur-containing compounds such as sulfolane, dimethylsulfoxide,3-sulfolene and the like; polyfunctional compounds such as diacetonealcohol, diethanolamine, and the like; and urea derivatives. Of these,polyhydric alcohols such as glycerin, diethylene glycol and the like aremore preferable. The drying inhibitor may be used singly or two or moreof them may be used in combination. The drying inhibitor is preferablycontained in the ink is in an amount of 10 to 50% by mass.

The penetration accelerator is preferably used for the purpose of betterpenetration of the inkjet ink into paper. As the penetrationaccelerator, alcohols such as ethanol, isopropanol, butanol,di(tri)ethylene glycol monobutyl ether, 1,2-hexanediol and the like;sodium lauryl sulfate, sodium oleate, nonionic surfactants, and the likecan be used. When the penetration accelerator is contained in the ink inan amount of 5 to 30% by mass, sufficient effects are usually exhibited,and it is preferable to use it within a range where bleeding of theprinted characters or print-through do not occur.

The ultraviolet ray absorber is used for the purpose of enhancing thestorability of images. As the ultraviolet ray absorber, usable are thebenzotriazole-based compounds described in JP-A-58-185677,JP-A-61-190537, JP-A-2-782, JP-A-5-197075, JP-A-9-34057, and the like;the benzophenone-based compounds described in JP-A-46-2784,JP-A-5-194483, U.S. Pat. No. 3,214,463 and the like; the cinnamicacid-based compounds described in JP-B-48-30492 (the term “JP-B” as usedherein means an “examined Japanese patent publication”.) andJP-B-56-21141, JP-A-10-88106 and the like; the triazine-based compoundsdescribed in JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621,JP-W-8-501291 (the term “JP-W” as used herein means a “publishedJapanese translation of a PCT patent application”.), and the like;compounds described in Research Disclosure No. 24239; and compounds thatabsorb ultraviolet ray and emit fluorescent light, so-called fluorescentbrightening agents, represented by stilbene-based compounds andbenzooxazole-based compounds.

The fading-preventing agent is used for the purpose of enhancing thestorability of images. As the fading-preventing agent, various organicor metal complex-based fading-preventing agents can be used. Examples ofthe organic fading-preventing agents include hydroquinones,alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes,chromans, alkoxyanilines, heterocyclic compounds, and the like. Examplesof metal complex fading-preventing agents include nickel complexes, zinccomplexes, and the like. Concretely, there can be used compoundsdescribed in the patents cited in Research Disclosure No. 17643 ChapterVII, items I to J, ibid., No. 15162, ibid., No. 18716, page 650, leftcolumn, ibid., No. 36544, page 527, ibid., No. 307105, page 872, ibid.,No. 15162; compounds falling within the general formulas ofrepresentative compounds and compound examples described inJP-A-62-215272, pages 127 to 137.

Examples of the anti-fungal agent include sodium dehydroacetate, sodiumbenzoate, sodium pyridinethion-1-oxide, ethyl p-hydroxybenzoate,1,2-benzoisothiazolin-3-on, and salts thereof. It is preferable to usethe anti-fungal agent in the ink in an amount of 0.02 to 1.00% by mass.

As the pH regulator, the above neutralizing agents (organic bases andinorganic alkali) can be used. For the purpose of enhancing the storagestability of the inkjet recording ink, the pH regulator is added suchthat the inkjet recording ink preferably has a pH of 6 to 10, and morepreferably a pH of 7 to 10.

Examples of the surface tension regulator include nonionic, cationic, oranionic surfactants. The surface tension of the inkjet recording inkcomposition of the invention is preferably from 20 to 60 mN/m, and morepreferably from 25 to 45 mN/m. The viscosity of the inkjet recording inkcomposition of the invention is preferably regulated to 30 mPa·s or lessand more preferably 20 mPa·s or less.

Examples of the surfactant preferably include anionic surfactants suchas fatty acid salts, alkyl sulfate salts, alkylbenzenesulfonic acidsalts, alkylnaphthalenesulfonic acid salts, dialkylsulfosuccinic acidsalts, alkyl phosphate salts, naphthalenesulfonic acid formalincondensate, polyoxyethylenealkyl sulfate salts and the like; andnonionic surfactants such as polyoxyethylene alkyl ether,polyoxyethylenealkyl allyl ether, polyoxyethylene fatty acid esters,sorbitan fatty acid esters, polyoxyethylenesorbitan fatty acid esters,polyoxyethylenealkylamine, glycerin fatty acid esters,oxyethyleneoxypropylene block copolymers, and the like. Also, SURFYNOLS(Air Products & Chemicals), which is an acetylene-typepolyoxyethyleneoxide surfactant is preferably used. Moreover, amineoxide-type amphoteric surfactants such as N,N-dimethyl-N-alkylamineoxide and the like is preferable. Furthermore, surfactants described inJP-A-59-157636, pp. 37-38 and Research Disclosure, No. 308119 (1989) canbe also used.

As the antifoaming agent, fluorine-containing compounds, silicone typecompounds, and chelating agents represented by EDTA can be used, ifnecessary.

When the abovementioned specific azo compound is dispersed into anaqueous medium, it is preferable to disperse colored fine particlescontaining a dye and an oil-soluble polymer into the aqueous medium asdescribed in JP-A-11-286637 and Japanese Patent Application Nos.2000-78491, 2000-80259, and 2000-62370 (which correspond toJP-A-2001-240763, JP-A-2001-262039, and JP-A-2001-247788, respectively),or to disperse the dye of the invention dissolved in a high-boilingpoint organic solvent into the aqueous medium as described in JapanesePatent Application Nos. 2000-78454, 2000-78491, 2000-203856, and2000-203857 (which correspond to JP-A-2001-262018, JP-A-2001-240763,JP-A-2001-335734, and JP-A-2002-80772, respectively).

As the specific method in case where the above specific azo compound isdispersed in an aqueous medium, the oil-soluble polymer to be used, thehigh-boiling organic solvent, the additives, and the amount thereof,those described in the above publications may be preferably used.Alternatively, the above azo dye can be dispersed in a solid state toform a fine particle state. At the time of dispersing, a dispersingagent or a surfactant can be used.

As dispersing equipment, a simple stirrer or impeller, an in-line mixer,a mill (e.g., a colloid mill, a ball mill, a sand mill, an attritor, aroller mill, or an agitator mill), an ultrasonic disperser, and ahigh-pressure emulsifying disperser (a high-pressure homogenizer:specifically, GORING homogenizer, MICRO-FLUIDIZER, DeBEE 2000, etc. arecommercially available machines) can be employed. The details of methodsof preparing the inkjet recording ink composition are described inJP-A-5-148436, JP-A-5-295312, JP-A-7-97541, JP-A-7-82515, JP-A-7-118584,JP-A-11-286637, and J Japanese Patent Application No. 2000-87539 (whichcorresponds to JP-A-2001-271003) in addition to the above publications.These methods can also be utilized in the preparation of the inkjetrecording ink composition of the invention.

As the aqueous medium mentioned above, a mixture containing water as amain component and a water-miscible organic solvent as an optionalcomponent may be used. Examples of the water-miscible organic solventinclude alcohols (e.g., methanol, ethanol, propanol, iso-propanol,butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol,cyclohexanol, and benzylalcohol), polyhydric alcohols (e.g., ethyleneglycol, diethylene glycol, triethylene glycol, polyethylene glycol,propylene glycol, dipropylene glycol, polypropylene glycol, butyleneglycol, hexanediol, pentanediol, glycerin, hexanetriol, andthiodiglycol), glycol derivatives (e.g., ethylene glycol monomethylether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,diethylene glycol monomethyl ether, diethylene glycol monobutyl ether,propylene glycol monomethyl ether, propylene glycol monobutyl ether,dipropylene glycol monomethyl ether, triethylene glycol monomethylether, ethylene glycol diacetate, ethylene glycol monomethyl etheracetate, triethylene glycol monomethyl ether, triethylene glycolmonoethyl ether, ethylene glycol monophenyl ether, and tetraethyleneglycol monobutyl ether), amines (e.g., ethanolamine, diethanolamine,triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine,morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine,triethylenetetramine, polyethyleneimine, andtetramethylpropylenediamine), and other polar solvents (e.g., formamide,N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide,sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone,2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, andacetone). These water-miscible organic solvents may be used as a mixtureof two or more.

As the ink composition of the invention, it is preferable that theabovementioned specific azo compound is contained in an amount of 0.2parts by mass to 10 parts by mass in 100 parts by mass of the inkjetrecording ink composition. The ink composition of the invention maycontain other dyes together with the azo compound mentioned above. Inthe case that the other dyes are used, it is preferable that the totalcontent of the above azo compound and the other dyes falls within theabove range.

The ink composition of the invention can be used not only for theformation of single-color images but also for the formation offull-color images. For the formation of full-color images, amagenta-colored ink, a cyan-colored ink, and a yellow-colored ink can beused. In addition, for adjustment of color tone, a black-colored ink mayalso be used.

As the applicable yellow dye, any dye can be used. Examples include arylor heteryl azo dyes having phenols, naphthols, anilines, heterocycliccompounds such as pyrazolones and pyridones, open chain-type activemethylene compounds, and the like as coupling components (hereinafterreferred to as “coupler components”); azomethine dyes having openchain-type active methylene compounds and the like as couplercomponents; methine dyes such as benzylidene dyes and monomethine oxonoldyes; and quinone-based dyes such as naphthoquinone dyes andanthraquinone dyes. As the other dye species, quinophthalone dyes,nitro/nitroso dyes, acrydine dyes, acrydinone dyes, and the like can beenumerated.

As the applicable magenta dye, any dye can be used. Examples includearyl or heteryl azo dyes having phenols, naphthols, anilines, and thelike as coupler components; azomethine dyes having pyrazolones,pyrazolotriazoles, and the like as coupler components; methine dyes suchas arylidene dyes, styryl dyes, melocyanine dyes, cyanine dyes, andoxonol dyes; carbonium dyes such as diphenylmethane dyes,triphenylmethane dyes, and xanthene dyes; and quinone dyes such asnaphthoquinone dyes, anthraquinone dyes, and anthrapyridone dyes; fusedpolycyclic dyes such as dioxazine dyes; and the like.

As the applicable cyan dye, any dye can be used. Examples include arylor heteryl azo dyes having phenols, naphthols, anilines, and the like ascoupler components; azomethine dyes having phenols, naphthols,heterocyclic compounds such as pyrrolotriazoles, and the like as couplercomponents; polymethine dyes such as cyanine dyes, oxonol dyes, andmelocyanine dyes; carbonium dyes such as diphenylmethane dyes,triphenylmethane dyes, and xanthene dyes; phthalocyanine dyes;anthraquinone dyes; indigo/thioindigo dyes; and the like.

The above each dye may be a dye which expresses each color of yellow,magenta, and cyan when part of the chromophore dissolves. In that case,a counter cation may be an inorganic cation such as alkali metal orammonium, or an organic cation such as pyridinium or a quaternaryammonium salt, or may be a polymer cation having the cation as part ofthe structure.

As the applicable black color material, carbon black dispersion inaddition to dis-azo, tris-azo, and tetra-azo dyes can be enumerated.

[Inkjet Recording Method]

The following will explain the inkjet recording method.

The gist of the inkjet recording method of the invention is to form animage on an image-receiving material comprising a support havingprovided thereon an ink-receiving layer containing a white inorganicpigment particle using the above inkjet recording ink composition of theinvention.

The support to be used in the inkjet recording method of the inventionis not limited and examples thereof include chemical pulp such as LBKPand NBKP; mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP;used paper pulp such as DIP; synthetic paper; plastic film sheet; andthe like.

If necessary, hitherto known additives such as pigments, binders, sizingagents, fixing agents, cationic agents, and paper strength-reinforcingagents may be mixed therewith. The support may be formed by using anytype of machine such as a fourdrinier paper machine or a cylinder papermachine.

The thickness of the support is preferably about 10 to 250 μm, and theweight thereof is preferably 10 to 250 g/m².

The ink-receiving layer, as well as the back coat layer as needed, maybe provided onto the support. These layers may be provided directly orthe ink-receiving layer and back coat layer may be provided aftersubjected to size pressing or coating of an anchor coat layer usingstarch, polyvinyl alcohol or the like. The support may be subjected toflattening processing by a calendar device such as a machine calendar, aTG calendar, a soft calendar or the like.

As the support, papers or plastic films, the both surfaces of which arelaminated with a polyolefin (e.g., polyethylene, polystyrene,polyethyleneterephthalate, polybutene, and copolymers thereof), andplastic film are more preferably employed in the invention. It ispreferable to include in the polyolefin a white pigment (e.g., titaniumoxide or zinc oxide) or a tinting dye (e.g., cobalt blue, ultramarineblue, or neodymium oxide).

The ink-receiving layer to be provided on the support contains a pigmentand an aqueous binder. As the pigment, a white pigment is preferable.Examples of the white pigment include white inorganic pigments such ascalcium carbonate, kaolin, talc, clay, diatomaceous earth, syntheticamorphous silica, aluminum silicate, magnesium silicate, calciumsilicate, aluminum hydroxide, alumina, lithopone, zeolite, bariumsulfate, calcium sulfate, titanium dioxide, zinc sulfide, and zinccarbonate; and organic pigments such as styrene-based pigments, acrylicpigments, urea resins, and melamine resins.

As the white pigment contained in the ink-receiving layer, porousinorganic pigments are preferable, and particularly, synthetic amorphoussilica having a large pore area is particularly preferable. As thesynthetic amorphous silica, any of silicic anhydride obtained by the dryproduction process and hydrated silicic acid obtained by the wetproduction process can be used, and particularly, the hydrated silicicacid is desirably used.

Examples of the aqueous binder to be contained in the ink-receivinglayer include water soluble polymers such as polyvinyl alcohol,silanol-modified polyvinyl alcohol, starch, cationic starch, casein,gelatin, carboxymethyl cellulose, hydroxyethyl cellulose,polyvinylpyrrolidone, polyalkylene oxide, polyalkylene oxide derivativesand the like; water-dispersible polymers such as styrene-butadienelatex, acrylic emulsions, and the like; and the like.

The aqueous binder may be used singly, or two or more types may be usedin combination. Among them, polyvinyl alcohol and silanol-modifiedpolyvinyl alcohol are suitable from the standpoints of adhesion to thepigment and peeling resistance of the ink-receiving layer.

The ink-receiving layer may contains a mordant, a water-proofing agent,a light-resistance enhancing agent, a surfactant, and other additives inaddition to the pigment and the aqueous binder.

The mordant to be added into the ink-receiving layer is preferablyimmobilized, and hence, a polymer mordant is preferably used.

The polymer mordants are described in JP-A-48-28325, JP-A-54-74430,JP-A-54-124726, JP-A-55-22766, JP-A-55-142339, JP-A-60-23850,JP-A-60-23851, JP-A-60-23852, JP-A-60-23853, JP-A-60-57836,JP-A-60-60643, JP-A-60-118834, JP-A-60-122940, JP-A-60-122941,JP-A-60-122942, JP-A-60-235134, JP-A-1-161236, and U.S. Pat. Nos.2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386,4,193,800, 4,273,853, 4,282,305, and 4,450,224.

The image-receiving materials containing the polymer mordant describedon pages 212 to 215 of JP-A-1-161236 are particularly preferred. Whenthe polymer mordant described in this patent is used, not only imageshaving an excellent image quality are obtained, but alsolight-resistance of the images is improved.

The above water-proofing agent is effective for making the imageswaterproof. A cationic resin is particularly preferable as thewater-proofing agent. Examples of the cationic resin includepolyamidepolyamine epichlorohydrin, polyethyleneimine, polyaminesulfone,dimethyldiallyl ammonium chloride polymer, cationic polyacrylamide,colloidal silica, and the like. Among these cationic resins,polyamidepolyamine epichlorohydrin is particularly suitable. The contentof the cationic resin is preferably from 1 to 15% by mass, andparticularly preferably 3 to 10% by mass, based on the total solid massof the ink-receiving layer.

Examples of the light-resistance enhancing agent include zinc sulfate,zinc oxide, hindered amine-based antioxidants, benzotriazole-basedultraviolet absorbers such as benzophenone. Of these, zinc sulfate isparticularly suitable.

The abovementioned surfactant functions as a coating aid, a peelingimproving agent, a slippage improving agent, or an antistatic agent.Examples of the surfactants are described in JP-A-62-173463 andJP-A-62-183457. An organofluorine compound may be used instead of thesurfactant. Preferably, the organofluorine compound is hydrophobic.Examples of the organofluorine compound include fluorine-basedsurfactants, oily fluorine-based compounds (e.g., fluorocarbon oil), andsolid fluorine-based compound resins (e.g., tetrafluoroethylene resin).The organofluorine compounds are described in JP-B-57-9053 (columns 8 to17), and JP-A-61-20994 and JP-A-62-135826.

Examples of other additives to be added to the ink-receiving layerinclude a pigment dispersing agent, a thickener, an antifoaming agent, adye, a fluorescent brightener, an antiseptics, a pH regulator, a mattingagent, a film hardener, and the like. The ink-receiving layer may becomposed of one layer or two layers.

In the method of the invention, as mentioned above, a back coat layer isprovided on the support, if necessary. To the layer may be also addedvarious components.

As the usable components, a white pigment, an aqueous binder, and othercomponents are enumerated. Examples of the white pigment to be added tothe back coat layer include white inorganic pigments such asprecipitated calcium carbonate light, calcium carbonate heavy, kaolin,talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide,zinc sulfide, zinc carbonate, satin white, aluminum silicate,diatomaceous earth, calcium silicate, magnesium silicate, syntheticamorphous silica, colloidal silica, colloidal alumina, pseudoboehmite,aluminum hydroxide, alumina, lithopone, zeolite, hydrated halloysite,magnesium carbonate, magnesium hydroxide, and the like; and organicpigments such as styrene-based plastic pigments, acrylic plasticpigments, polyethylene, microcapsules, urea resins, melamine resins andthe like.

Examples of the aqueous binder include water soluble polymers such as astyrene/maleic acid salt copolymer, a styrene/acrylic acid saltcopolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol,starch, cationic starch, casein, gelatin, carboxymethyl cellulose,hydroxyethyl cellulose, and polyvinylpyrrolidone; waterdispersible-polymers such as styrene-butadiene latex, and acrylicemulsion; and the like. Examples of the other components to be containedin the back coat layer include an antifoaming agent, a foaminginhibitor, a dye, a fluorescent brightener, an antiseptic, awaterproofing agent, and the like.

A polymer latex may be added to the image-receiving material (inclusiveof the back coat layer, if necessary). The polymer latex is used for thepurpose of imparting glossiness or water resistance, improving weatherresistance, and improving the film properties such as dimensionalstability, prevention of curling, prevention of adhesion, and preventionof film cracks.

The timing of the addition of the polymer latex to the image-receivingmaterial may be before or after the addition of a colorant, or at thesame time of the addition. Therefore, the place to which the latex isadded may be in the image-receiving paper or in the ink, or the latexmay be used as a liquid of the polymer latex alone.

When a polymer latex having a low glass transition temperature (40° C.or lower) is added into the layer containing a mordant, cracking andcurling of the layer can be prevented. Furthermore, when a polymer latexhaving a high glass transition temperature is added into the backcoating layer, curling of the layer can be also prevented.

Specifically, methods disclosed in JP-A-62-245258, JP-A-62-1316648 andJP-A-62-110066 and Japanese Patent Application Nos. 2000-363090,2000-315231, 2000-354380, 2000-343944, 2000-268952, 2000-299465, and2000-297365 (which correspond to JP-A-2002-166638, JP-A-2002-121440,JP-A-2002-154201, JP-A-2002-144696, JP-A-2002-80759, JP-A-2002-187342,and JP-A-2002-172774, respectively) can be preferably used.

In the method of the invention, as the image-receiving materialcomprising the abovementioned support and the ink-receiving layer, knownimage-receiving materials can be employed.

That is, plain paper, resin-coated paper, paper specialized for inkjetrecording as described in, for example, JP-A-8-169172, JP-A-8-27693,JP-A-2-276670, JP-A-7-276789, JP-A-9-323475, JP-A-62-238783,JP-A-10-153989, JP-A-10-217473, JP-A-10-235995, JP-A-10-337947,JP-A-10-217597 and JP-A-10-337947, film, electrophotographic sharedpaper, cloth, glass, metal, ceramics, and the like may be enumerated.

The inkjet recording method of the invention comprises forming an imageon an image-receiving material by providing energy to the abovementionedinkjet recording ink composition. The inkjet recording mode is notlimited, and use can be suitably made of any of known modes, forexample, a charge control mode of discharging the ink utilizing anelectrostatic attracting force; a drop on demand mode (pressure pulsemode) of utilizing an oscillation pressure of piezoelectric elements; anacoustic ink jet mode of converting electric signals into acousticbeams, irradiating the ink with the beams, and discharging the inkutilizing the resulting radiation pressure; a thermal ink jet mode ofheating the ink to form air bubbles and utilizing the generatedpressure; and the like.

The inkjet recording mode includes a mode of injecting many drops of anink having a low density, called a photo-ink, in small volumes; a methodof improving image quality using a plurality of inks havingsubstantially the same hue and a different density; and a mode ofutilizing a colorless, transparent ink.

The following will describe the invention specifically with reference toExamples, but it should not be construed that the invention is limitedthereto.

EXAMPLE 1

(Preparation of Aqueous Ink)

Deionized water was added to the following components to made the volume1 liter, and then the whole was stirred under heating at 30 to 40° C.for 1 hour. Thereafter, the mixture was adjusted to pH 9 with 10 mol/lLiOH and filtered under reduced pressure through a microfilter having anaverage pore size of 0.25 μm to prepare a dye ink liquid.

Composition of Ink Liquid A

A dye of the invention (a-1)   25 g Diethylene glycol   20 g Glycerin 120 g Diethylene glycol monobutyl ether  230 g 2-Pyrrolidone   80 gTriethanolamine 17.9 g Benzotriazole 0.06 g Surfinol TG  8.5 g PROXELXL2  1.8 g

Ink liquids B to F for comparison were prepared in a similar manner tothe preparation of the ink liquid A with the exception that the abovedye was changed as shown in the following Table 8. In this connection,the numbers of the compound examples used as the dyes mean the numbersattached for the azo compounds shown as specific examples in the above,and the comparative dyes are compounds having the following structuralformulae.

(Image Recording and Evaluation)

An image was recorded on photo glossy paper (PM photo paper <glossy>(KA420PSK), manufactured by Seiko Epson Corporation) using each of theink liquids A to F and an inkjet printer (PM-700C, manufactured by SeikoEpson Corporation), and “Paper dependency”, “Light resistance”, “Ozonegas resistance”, and “Bleeding property” were evaluated on the obtainedeach image in accordance with the following methods.

<Paper Dependence>

The color tone of the image recorded on the above photo glossy paper andthat of an image separately recorded on plain paper for PPC werecompared. Each ink was evaluated on two grades, that is, ink exhibitinga small difference between the two was evaluated as A (good), and inkexhibiting a large difference between the two was evaluated as B (bad).

<Light Resistance>

The above photo glossy paper having an image formed thereon wasirradiated with a xenon light (85,000 lx) using a weatherometer (ATLASC. I65) for 7 days, and the image density before and after theirradiation with a xenon light was measured using a reflectiondensitometer (X-Rite 310TR) and evaluated as a dye retention rate.Incidentally, the above reflection density was measured at three pointsof 1, 1.5, and 2.0.

Each ink was evaluated on three grades, that is, ink having a dyeretention rate of 70% or more at any density was ranked as A, ink havinga dye retention rate of less than 70% at one or two points was ranked asB, and ink having a dye retention rate of less than 70% at all thedensities was ranked as C.

<Ozone Gas Resistance>

The above photo glossy paper having an image formed thereon was allowedto stand in a dark box at room temperature under an ozone gasconcentration of 0.5 ppm for 7 days and the image density before andafter the standing under ozone gas was measured using a reflectiondensitometer (X-Rite 310TR) and evaluated as a dye retention rate.Incidentally, the above reflection density was measured at three pointsof 1, 1.5, and 2.0. The concentration of ozone gas in the box was setusing an ozone gas monitor (Model: OZG-EM-01) manufactured by APPLICS.

Each ink was evaluated on three grades, that is, ink having a dyeretention rate of 70% or more at any density was ranked as A, ink havinga dye retention rate of less than 70% at one or two points was ranked asB, and ink having a dye retention rate of less than 70% at all thedensities was ranked as C.

<Bleeding Property>

The above photo glossy paper having an image formed thereon was storedunder conditions of 25° C. and 90% RH for 3 days and the bleeding beforeand after the storage was visually evaluated. Each ink was evaluated onthree grades, that is, ink exhibiting no bleeding was ranked as A, inkexhibiting slight bleeding was ranked as B, and ink exhibiting muchbleeding was ranked as C.

TABLE 8 Paper Water Light Dark Ozone depen- resis- resis- heat resis-Bleed- Ink Dye dency tance tance storability tance ing A a-1 A A A A A AB c-7 A A A A A A C e-2 A A A A A A D i-1 A A A A A A E Compar- A A B AC C ative dye 1 F Compar- A A B A C C ative dye 2(Oxidation Potential of Dye)

The oxidation potential of each dye used in Examples and ComparativeExamples was determined by the following method.

A value was measured in N,N-dimethylformamide containing 0.1 mol·dm⁻³ oftetrapropylammonium perchlorate as a supporting electrolyte (dyeconcentration: 1×10⁻³ mol·dm⁻³) by direct current polarography using agraphite electrode and POLAROGRAPHIC ANALYZER P-100. The results of themeasurement are shown in the following Table 9.

TABLE 9 Oxidation Ink Dye potential A a-1 1.42 Invention C e-2 1.30Invention E Comparative 0.69 Comparative dye 1 Example F Comparative0.71 Comparative dye 2 Example

The comparative dyes given in Table 8 are as follows.

As shown in Table 8, it is apparent that the images obtained by usingthe ink liquids of the invention are more excellent in lightfastness andozone gas resistance as compared with the images obtained from thecomparative ink liquids E and F.

Furthermore, images were recorded on superfine specialized glossy paper(MJA4S3P, manufactured by Seiko Epson Corporation) by means of an inkjetprinter (PM-700C, manufactured by Seiko Epson Corporation) using the inkliquids A to F. Upon the evaluation of hue, lightfastness, and ozone gasresistance of the obtained images, results similar to those in Table 8were obtained in all cases.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

This application is based on Japanese patent applications No.2002-113460 filed on Apr. 16, 2002, and No. 2002-281723 filed on Sep.26, 2002, the entire contents thereof being hereby incorporated byreference.

INDUSTRIAL APPLICABILITY

Since the coloring composition of the invention uses a novel azocompound having an excellent water resistance and a sufficient fastnessto light, heat, humidity, and active gases in the environment as a blackdye, colored images excellent in water resistance and fastness areobtained and hence, the coloring composition is suitably used as aprinting ink composition, e.g., an inkjet recording ink composition.

Moreover, by the inkjet recording ink composition of the invention andthe inkjet recording method using the composition, it is possible toform images having an excellent water resistance and a high fastness tolight and active gases in the environment, particularly ozone gas.

1. A coloring composition comprising a dis-azo compound or poly-azocompound which contains two or more substituents having a pKa value inwater of −10 to 5 and which has an oxidation potential more positivethan 0.8 V (vs SCE), wherein the dis-azo compound or poly-azo compoundis an azo compound represented by the following general formula (I):A—N═N—B—N═N—C  (I) wherein A, B, and C each independently represents anaromatic group which may be substituted or a heterocyclic group whichmay be substituted, A and C are monovalent groups and B is a divalentaromatic heterocyclic group directly bonded to the azo-nitrogen atoms.2. The coloring composition according to claim 1, wherein the dis-azocompound or poly-azo compound is an azo compound represented by thefollowing general formula (II):A—N═N—B—N═N-Het  (II) wherein A and B are the same as A and B in thegeneral formula (I) respectively, and Het represents an aromaticheterocyclic group.
 3. The coloring composition according to claim 2,wherein at least one of A and B in the general formula (II) is anaromatic heterocyclic group.
 4. The coloring composition according toclaim 2, wherein Het in the general formula (II) is an aromaticnitrogen-containing six-membered heterocyclic group.
 5. The coloringcomposition according to claim 2, wherein the dis-azo compound orpoly-azo compound is an azo compound represented by the followinggeneral formula (III):

wherein A and B are the same as A and B in the general formula (II)respectively, B₁ and B₂ represent ═CR₁— and —CR₂═ respectively, oreither one represents a nitrogen atom and the other represents ═CR₁— or—CR₂═; G, R₁ and R₂ each independently represents a hydrogen atom, ahalogen atom, an aliphatic group, an aromatic group, a heterocyclicgroup, a cyano group, a carboxyl group, a carbamoyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclicoxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group, anaryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxygroup, a carbamoyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group (including an anilino group anda heterocyclic amino group), an acylamino group, a ureido group, asulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkyl- or arylsulfonylamino group, aheterocyclic sulfonylamino group, a nitro group, an alkyl- or arylthiogroup, a heterocyclic thio group, an alkyl- or arylsulfonyl group, aheterocyclic sulfonyl group, an alkyl- or arylsulfinyl group, aheterocyclic sulfinyl group, a sulfamoyl group, or a sulfo group, andeach of these groups may further be substituted; R₅ and R₆ eachindependently represents a hydrogen atom, an aliphatic group, anaromatic group, a heterocyclic group, an acyl group, an alkoxycarbonylgroup, an aryloxycarbonyl group, a carbamoyl group, an alkyl- orarylsulfonyl group, or a sulfamoyl group, and each of these groups mayfurther be substituted, provided that R₅ and R₆ are not hydrogen atomsat the same time; and R₁ and R₅ or R₅ and R₆ may be combined to form afive-membered or six-membered ring.
 6. The coloring compositionaccording to claim 5, wherein the dis-azo compound or poly-azo compoundis an azo compound represented by the following general formula (IV):

wherein A, B₁, B₂, G, R₅ and R₆ are the same as A, B₁, B₂, G, R₅ and R₆in the general formula (III) respectively, and R₇ and R₈ are the same asR₁ in the general formula (III).
 7. An inkjet recording ink composition,which comprises the coloring composition according to claim
 1. 8. Aninkjet recording method, wherein an image is formed on animage-receiving material comprising a support having provided thereon anink receiving layer containing a white inorganic pigment particle, usingthe inkjet recording ink composition according to claim
 7. 9. A methodfor improving ozone gas-fastness of an image formed on animage-receiving material comprising a support having provided thereon anink receiving layer containing a white inorganic pigment particle usingan inkjet recording ink composition, wherein the inkjet recording inkcomposition is the inkjet recording ink composition according to claim7.
 10. An inkjet recording ink composition, which comprises the coloringcomposition according to claim
 2. 11. An inkjet recording inkcomposition, which comprises the coloring composition according to claim3.
 12. An inkjet recording ink composition, which comprises the coloringcomposition according to claim
 4. 13. An inkjet recording inkcomposition, which comprises the coloring composition according to claim4.
 14. An inkjet recording ink composition, which comprises the coloringcomposition according to claim
 6. 15. The coloring composition accordingto claim 1, wherein the heterocyclic group of B is selected from thegroup consisting of a thiophene ring, a thiazole ring, an imidazolering, a benzothiazole ring and a thienothiazole ring.